The present invention is related to integrated circuit packaging and in particular to embedding memory in the same packages as an integrated circuit.
One of the limitations of speed on a personal computer are the signal leads or traces on the motherboard that connect the microprocessor to memory devices such as random access memory. The length of the traces directly affects the speed at which signals can be exchanged between the microprocessor and the memory. Therefore, computer designers locate the memory as close to the microprocessor as possible within design constraints imposed by other components and the configuration of standard motherboards. As the complexity of personal computers increases and the size of the computer chassis decreases, the layout of the motherboard becomes a critical design limitation because of the clearances required between components on the motherboard, and between the motherboard and other integrated circuit boards in the chassis.
One solution to minimize the length of the traces has been to package the memory and the microprocessor together in the same assembly. However, doing so without radically modifying the configuration of the motherboard requires changing the die sizes of either the memory, the microprocessor, or both.
Therefore, there is a need for a combined microprocessor/memory assembly that minimizes the length of the traces without requiring changes to the die sizes of the microprocessor, the memory, or to the configuration of the motherboard.
Memory devices, such as random access memory, are affixed onto an electrical contact frame and coupled to signals lines on the frame which is, in turn, mounted on a top surface of an integrated circuit, such as a microprocessor, a controller chip, or an ASIC (application-specific integrated circuit). The signal leads are coupled to electrical contact pads disposed on the top surface of the integrated circuit. The signal leads carry the control and power signals between the integrated circuit and the memory.
The electrical contact pads are arranged in the center of the top surface of the integrated circuit. The signal leads are coupled to the electrical contact pads through ball bonds or metal pillars. Alternatively, the electrical contact pads are disposed around the perimeter of the top surface of the integrated circuit coupled to the signal leads through conventional bonding techniques.
The embedded memory assembly minimizes the signal leads running between the integrated circuit and the memory without requiring changes to the die sizes of the integrated circuit or the memory. Therefore, the profile of the integrated circuit is increased only minimally by the contact frame and the memory, requiring few, if any, changes in existing manufacturing techniques while increasing signal transfer speed between the integrated circuit and the memory.
When the embedded memory assembly is used in conjunction with a microprocessor for a computer, major modifications to the configuration of the motherboard and to the computer chassis are unnecessary. Thus, the embedded memory assembly allows a computer manufacturer greater design freedom without sacrificing computer performance.